The present invention relates in general to means for controlling the flow of air into and out of a building, and, more particularly, to louvers.
In the construction of a building, there are certain areas which require the availability of fresh air. These areas usually are provided by defining a port in a building outside element, such as a wall, through which air moves into and/or out of the buidling. In order to properly modify the air flow through the port, and to protect the interior of the building from material passing thereinto from the building exterior, louvers are usually positioned in the building port.
As used herein, the term "louver" refers to an opening in a building wall or ceiling with slanted or sloping slats which allow sun and ventilation, but which exclude rain. The louver slats may be fixed or adjustable and may be any arrangement of fixed or adjustable slat-like openings which provide ventilation. Furthermore, as used herein, the term "louver blade" refers to the series of sloping slats which function to permit light and air to enter the building, but which are intended to exclude water infiltration into the building, and, especially, to shed rain water outward.
There are at least two basic criteria to be considered in the design of louvers. The first criterion is concerned with establishing proper air flow through the port, and the second criterion is concerned with preventing unwanted material, such as birds, water, debris, or the like, from passing through the port. Of the two cirteria, the first is generally considered to be the more important.
The establishment of proper air flow through the louver includes several considerations. For example, constriction of air flow through the port by the louver should be minimized. In other words, the percentage of the port opening that is restricted by the louver blades themselves should be minimized, so that pressure drop of the air passing through the port over the louver blades is as low as possible. Those skilled in the art will realize that any body placed in a flow stream will affect the pressure drop of the flow adjacent that body, and hence any louver blade will tend to restrict the opening and therefor create a pressure drop; however, a design consideration still should include minimizing this pressure drop.
Another consideration involved in the establishment of proper air flow through the port involves the prevention of water infiltration into the building. Ambient air may have varying amounts of moisture entrained therein due to many reasons, such as, for example, humidity, rain, fog, snow, or the like. When such moisture laden air strikes the louver blades, the moisture contained therein may tend to condense onto the louver blades or be carried into the building via the port. In designing the configuration of the louver blade itself, one of the primary purposes is to reduce or eliminate water infiltration. Water infiltration is generally determined by ounces per square foot of louver surface based upon wind velocity of varying speeds.
There are louvers designed to control the amount of water or moisture flowing into a building in the air passing through the port. A louver design includes an inwardly facing piece of metal on the upper front edge of the louver. This piece of metal allows the water that is running down the face of the building to be directed along the surface of the inwardly facing lip, and, when that water reaches the end of the lip, to drop off and fall into a trough formed in the topmost louver blade. The water is then carried back to the side of the louver to be transported away therefrom by a suitable drainage system. The back of the topmost louver blade is squared off so that none of the water on the upper blade can be blown into the inside of the louver. These louvers may also include louver blades which have a back lip for catching water.
However, it has been found through experimentation that when water runs off a surface above a louver blade, such as the lower surface of a superjacent louver blade, that water splashes and those splashes are carried into the interior of the louvered area by the air flowing through the louver. Thus, the splashes vitiate the effect of the moisture control device of those known louver blades because of the reinsertion of some moisture into the flowing air.
As used herein, the term "splashes" refers to that liquid caused to fly or scatter by the falling and striking of water against a surface, such as a louver blade. Thus, that mass of water generated by the falling and striking of water against a louver blade is referred to as either "splashes" or "droplets".
Accordingly, those louver blades having a front lip, while somewhat effective at controlling the moisture content of the air flowing into a building via the louver, are still unsatisfactory because these designs do not account for any moisture reinserted into the flowing air by the just-discussed splashing effect.
Other known louvers include inverted V-shaped blades which do not have the just-discussed front lips, and do not account at all for the just-discussed splashing effects. Still other known louvers include louver blades having V-shaped (see, e.g., U.S. Pat. No. 3,287,870) or inverted V-shaped ridges located near the middle thereof. However, these known blades are not effective to account for the droplets generated by the splashing of water onto the blade. Such droplets may fly upward from the blade high enough to clear the obstruction formed by the inverted ridge and to be carried thereover by the airstream. Furthermore, under certain conditions, water can flow over such a ridge and thereby obviate any effect of that ridge.
Another disadvantage of known louvers involves the bottom opening thereof. In known devices, the size of the rear opening is substantially larger than the front opening. This size differential results in an excessive amount of moisture being carried from the lowermost louver blade into the interior of the louver.
Accordingly, there is need of a louver which accounts for the droplets generated from water splashing when water falls onto a louver blade from above, and which will prevent water from circumventing any water catching device defined on the blade.